Vemurafenib Receives FDA Approval for Treating Erdheim Chester Disease

On 6 November 2017, the United States Food and Drug Administration FDAapproved vemurafenib (trade name Zelboraf) for treating Erdheim Chester disease positive for the BRAF V600 mutation.

Approval was based on an open-label, multicenter, single-arm, multicohort clinical trial in patients aged 16 and older. The trial included BRAF V600 mutation positive patients with Erdheim-Chester disease, 22 in total. Among the 22 receiving vemurafenib, 12 (%54.5) responded to treatment. In 11 patients, partial responses (% 50) were observed, and in one patient a complete response (%4.5). Median follow-up was 26.6 months, and median time to response was reported as 11 months.

In the study, among patients with Erdheim Chester disease and the BRAF V600 mutation, the most commonly reported (>% 50) side effects were joint pain, rash, warts, hair loss, fatigue and heart disorders. The most common severe (grade ≥ 3) side effects were secondary skin cancers, hypertension, rash and joint pain. Treatment discontinuation due to side effects was %32.

The recommended vemurafenib dose is taken approximately 12 hours apart, twice daily orally, with or without food, at 960 mg.

What Is Erdheim-Chester Disease?

Erdheim-Chester disease a rare non-Langerhans histiocytic disorder, is most commonly characterized by multifocal osteosclerotic lesions of long bones (histiocytes are a special type of white blood cell). The most common symptom is bone pain. It may involve many organs, including the brain and heart. Its tumors are characterized on biopsy by sheets of foamy histiocytes and invasion of nonbone tissues by histiocyte cells. Erdheim-Chester disease was described in 1930 by Erdheim and Chester. Its cause is not fully known. Only a few hundred cases have been reported in medical literature since then.

The radiograph below shows bone involvement around the thigh and knee caused by Erdheim-Chester disease.